A receiving terminal in a wireless charging system that uses electromagnetic induction may include a magnetic disk that may absorb electromagnetic waves entering into the material of the receiving terminal, which may prevent the electromagnetic wave from interfering with the electromagnetic signals of the receiving terminal, and/or prevent the electromagnetic waves from generating heat in components of the receiving terminal, e.g., batteries and etc. Currently, composite materials, such as a composite material made from an Al—Si—Fe alloy and a resin, are used for making the magnetic disk. However, the particles of the Al—Si—Fe alloy need to have a uniform and fixed shape, and the arrangement of the particles in the resin need to be aligned in accordance with a certain orientation; otherwise, the initial magnetic permeability of the composite material can be very low. Even if the arrangement of the particles in the resin are aligned along a desirable orientation, the initial magnetic permeability of the composite material may not be high due to the existence of an amount of resin. Moreover, the resistivity of the composite material may be relatively high because of the existence of metals. These disadvantages may lead to a low efficiency and poor safety of the wireless charging system, and more pronounced electromagnetic heating effect on the components of the receiving terminal, such as the battery.
Chinese Patent Application No. CN 102211929 A discloses a NiCuZn ferrite material that is sintered at a low temperature and has high magnetic permittivity. The Ni—Cu—Zn ferrite material contains a main composition selected from the group consisting of Fe2O3, ZnO, CuO, and NiO, and an auxiliary composition selected from the group consisting of NaCO3, B2O3, and Ta2O5. Among the oxide components in the main composition, Fe2O3, ranges from 40.5 mol % to 49.6 mol %; ZnO, ranges from 30 mol % to 47 mol %; CuO ranges from 5 mol % to 20 mol %; and the remaining of the oxide components is NiO. Based on the total weight of the main composition, the sum of the auxiliary composition ranges from 0.16 wt % to 1.65 wt %. The NiCuZn ferrite material has a relatively high magnetic conductivity, but the material has a relatively high magnetic loss.